It is known to provide a drum-type drier in which a drying drum is rotably mounted in a housing and has a horizontal axis, means being provided to effect a passage of a drying gas, generally heated air or some other gas, generally radially through the fabric web which is guided onto and passes around the perforated periphery of the drum.
In this system, the housing may be formed with a slot or gap in at least one of the vertical longitudinal walls through which the fabric web enters the housing and leaves the housing, the web passing over suitable guide means. Within the housing the web lies upon the major part of the cylindrical surface of the perforated drum and means is provided for inducing a flow of the drying gas through the fabric web while the latter is on the drum. Generally the drying gas is air, as noted previously, the air being heated in a heat exchanger, passing through the fabric web and the drum in a radial direction, and being cooled in a condenser or the like at which moisture is removed from the air. The air can then be recirculated to the heater and discharged into the atmosphere.
The displacement of the air stream is effected generally by a blower or fan. In most prior-art systems of this type, the cooler is disposed externally of the housing and is traversed by the moisture-laden air stream or the air stream laden with vapors of a solvent with which the fabric has been treated. Generally the fabric to be dried contains water or an organic solvent, the fabric arriving from a fabric-treatment station, e.g. a dyeing installation.
In the external cooler, the vapors of the treating liquid, e.g. water or organic solvent such as perchloroethylene, are condensed.
Usually and preferably, the air after contact with the cooler is recirculated, i.e. is displaced in a closed cycle from the cooler to an air heater before the air flows anew into contact with the textile web covering the major part of the cylindrical periphery of the drum.
Arrangements in which the cooler or, more generally, the heat exchanger for contact with the air stream and vapor condensation, is located externally of the housing are space-consuming and pose problems with respect to sealing against the environment. Frequently the heat exchanger is relatively inaccessible for maintenance and, if accessible at all, requires time-consuming measures to obtain access.